The present disclosure relates generally to refrigerators, and more particularly to a defrost heater system for a refrigerator.
Most refrigerators, such as that as disclosed in U.S. Pat. No. 5,711,159, include an evaporator which normally operates at sub-freezing temperatures in an evaporator compartment positioned behind the freezer compartment. A layer of frost typically builds up on the surface of the evaporator. As disclosed in U.S. Pat. No. 5,042,267, filed on Oct. 5, 1990, and assigned to General Electric Company, assignee of the present invention, a radiant heater is often positioned inside a housing and below the evaporator to warm the evaporator by both convection and radiant heating in order to quickly defrost the evaporator.
However, existing radiant defrost heaters consume a significant amount of energy. Also, radiant defrost heaters typically require a metal enclosure or housing to protect the heating element(s), as well as prevent other objects from contacting the heating element(s). This adds to material, space and cost requirements. Due to the high operating temperatures of radiant defrost heaters, ice in the freezer compartment ice bucket has a tendency to fuse during the defrost process. While some designs to reduce ice fusing can include the use of tubular resistance heaters, these heaters tend to be more expensive than radiant heaters, and still consume a considerable amount of energy. Moreover, they do not lend themselves well to use with some evaporator configurations, such as, for example, spine fin evaporators. For refrigerators that utilize flammable refrigerants, such as for example, isobutene, the use of radiant heaters results in a risk of igniting refrigerant in case of a leak.
Accordingly, it would be desirable to provide an efficient defrost system in a refrigerator that addresses the problems identified above.